Commit e286b6c1 authored by Sergey Senozhatsky's avatar Sergey Senozhatsky Committed by Greg Kroah-Hartman

zram: restrict add/remove attributes to root only

commit 5c7e9ccd upstream.

zram hot_add sysfs attribute is a very 'special' attribute - reading
from it creates a new uninitialized zram device.  This file, by a
mistake, can be read by a 'normal' user at the moment, while only root
must be able to create a new zram device, therefore hot_add attribute
must have S_IRUSR mode, not S_IRUGO.

[akpm@linux-foundation.org: s/sence/sense/, reflow comment to use 80 cols]
Fixes: 6566d1a3 ("zram: add dynamic device add/remove functionality")
Link: http://lkml.kernel.org/r/20161205155845.20129-1-sergey.senozhatsky@gmail.comSigned-off-by: default avatarSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reported-by: default avatarSteven Allen <steven@stebalien.com>
Acked-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent a0bd6aa0
...@@ -1378,8 +1378,14 @@ static ssize_t hot_remove_store(struct class *class, ...@@ -1378,8 +1378,14 @@ static ssize_t hot_remove_store(struct class *class,
return ret ? ret : count; return ret ? ret : count;
} }
/*
* NOTE: hot_add attribute is not the usual read-only sysfs attribute. In a
* sense that reading from this file does alter the state of your system -- it
* creates a new un-initialized zram device and returns back this device's
* device_id (or an error code if it fails to create a new device).
*/
static struct class_attribute zram_control_class_attrs[] = { static struct class_attribute zram_control_class_attrs[] = {
__ATTR_RO(hot_add), __ATTR(hot_add, 0400, hot_add_show, NULL),
__ATTR_WO(hot_remove), __ATTR_WO(hot_remove),
__ATTR_NULL, __ATTR_NULL,
}; };
......
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